EP0783438B1

EP0783438B1 - A method and machines for decorating cooking vessels

Info

Publication number: EP0783438B1
Application number: EP95934626A
Authority: EP
Inventors: Franco Libe'
Original assignee: Rondine Italia SpA
Current assignee: Bialetti Industrie SpA
Priority date: 1994-09-26
Filing date: 1995-09-22
Publication date: 1998-06-10
Anticipated expiration: 2015-09-22
Also published as: AU3698395A; EP0783438A1; WO1996009966A1; DE69502961T2; DE69502961D1; ES2120769T3

Abstract

In order to decorate cooking vessels, the vessel is coated with silicone resin at least on the surface to be decorated, a carrier, to which a heat releasable decoration is applied, is provided, and the carrier is brought into contact with the coated surface of the vessel to be decorated, heat being supplied so as to transfer the decoration to the coated surface of the vessel. The carrier may be configured as a ribbon (30). The vessel (15) is fitted on a heated form (14), a drum (35), which is also heated, keeps the ribbon (30) in contact with the vessel (15), and the drum (35), the vessel (15), and the ribbon (30) are moved so as to transfer the decoration onto the vessel (15). Cooking vessels (15) can thus be decorated easily, cheaply, and permanently with any decoration.

Description

The subject of the present invention is a method of decorating cooking vessels such as pots, saucepans, frying-pans, baking-pans, roasters, etc., and machines for implementing the method.

The prior art provides for the use of silk-screen-printing or flexographic printing methods for decorating cooking vessels.

In silk-screen printing, the surface of the vessel to be decorated is inked by means of the yarn of a screen which is left permeable to the ink in the regions of images to be reproduced and impermeable in the other regions.

In flexographic printing, on the other hand, the surface to be decorated is inked by means of a roller having raised portions which reproduce the decoration.

With reference to a frying-pan, which is formed by the drawing of a flat disc, the decoration can be printed by silk-screen or flexographic techniques and, in both cases, is printed on the disc before drawing. Unfortunately, the subsequent drawing deforms the decoration and this considerably limits the selection of the type of decoration which, naturally, must not suffer aesthetically as a result of the deformation. Moreover, if a multi-coloured decoration is desired, several very precise silk-screen-printing or flexographic passes are necessary and this considerably affects production times and costs.

For enamelled saucepans, the silk-screen technique is used but, unlike frying-pans, these are silk-screen printed on their already-formed cylindrical lateral surfaces by the rotation of the saucepan and the translation of the screen. In this case the decoration is not deformed but, if a multi-coloured decoration is desired, several very precise silk-screen-printing passes are always necessary, with consequent long production times and high production costs.

The UK Patent Application GB-A-2131744 describes that it is known to apply decorative designs to hollow-ware such as cups, mugs and the like, using heat releasable transfers mounted on a carrier; the hollow-ware is heated to a temperature of approximately 140°C so that it is sufficiently hot to melt the heat releasable transfer and the transfer is then applied to the surface of the hollow-ware item. This method overcome the aforesaid inconveniences of the other methods. However the cooking vessels are subject in use to high temperatures and the decorative design applied on the surface of the cooking vessel using a heat releasable transfer would be damaged.

The object of the present invention is to prevent the aforementioned problems, using a heat releasable transfer without the aforesaid drawback of the same.

This object is achieved by means of a method according to claim 1 and by machines as defined in

claims

10 and 24.

The vessel may be formed from a plate and the silicone resin is applied to the plate before forming the vessel. Also the decoration may be applied to the plate before forming the vessel.

For a better understanding of the invention, examples of the method according to the invention and machines for the heat transfer of the decoration to the vessel or to the plate from which the vessel are formed, are described below by way of example and are illustrated in the appended drawings in which:

Figure 1 is a front perspective view of a first machine for decorating cooking vessels,

Figure 2 is a rear perspective view of a portion of said first machine,

Figures 3 and 4 show the operation of a device for regulating said first machine.

Figure 5 is a front perspective view of a second machine for decorating cooking vessels,

Figure 6 is a rear, enlarged, perspective view of said second machine,

Figure 7 is a front perspective view of a third machine for decorating plates from which cooking vessels are formed.

An example of method of decorating a cooking vessel formed from a plate comprises the following steps.

The plate is coated with silicone resin by known technique and is heated to a temperature comprised between 130°C and 200°C, preferably 170°C.

The plate is allowed to cool to room temperature and is moulded by known technique to form the vessel.

The vessel is heated to a temperature comprised between 80°C and 100°C, preferably 90°C. A carrier of polythene paper, carrying a heat releasable decoration, is brought into contact with the surface of the vessel to be decorated. Heat is supplied to transfer the decoration to the coated surface of the vessel: the transfer temperature is comprised between 100°C and 120°C, preferably 110°C.

The vessel is then heated to a temperature comprised between 180°C and 220°C, preferably 200°C, to fix the silicone resin coating and the decoration on the vessel.

Another example of method of decorating a cooking vessel formed from a plate comprises the following steps.

The plate is coated with silicone resin by known technique and is heated to a temperature comprised between 80°C and 100°C, preferably 90°C.

A carrier of polythene paper, carrying a heat releasable decoration, is brought into contact with the surface of the plate. Heat is supplied to transfer the decoration to the coated surface of the plate: the transfer temperature is comprised between 100°C and 120°C, preferably 110°C.

The plate is heated to a temperature comprised between 180°C and 220°C, preferably 200°C, to fix the silicone resin coating and the decoration on the plate.

By virtue of what has been described in the examples given above, the problems of the silk-screen-printing and flexographic techniques mentioned in the introduction in the decoration of cooking vessels are solved.

In fact, as regards the first example of method, the decoration is applied to the already-formed vessel and there is therefore no deformation of the decoration as a result of the forming of the vessel.

In the case of a multi-coloured decoration, as stated above, a heat releasable multi-coloured decoration can be applied to the carrier and then transferred to the vessel or to the plate in a single pass and not in several passes which, above all, avoids the precision working required by several passes.

This means that production times and costs are low in comparison with the silk-screen-printing and flexographic techniques, even taking into account the costs of the carrier with the decoration which, as is known, can be produced quickly and cheaply.

The silicone resin coating enables the decoration to be fixed to the vessel firmly and in an aesthetically optimal manner. The heat treatments at said specific temperatures enhances such features.

The three machines for the heat transfer of the decoration will be thereinafter described, the first and second of which refer to the first example of method described above and the third of which refers to the second example of method described above.

The first machine, shown in the Figures 1,2,3,4 and generally indicated 10, is suitable for decorating pots and is vertically operating.

The machine comprises a support structure 11 for supporting the various members of the machine.

A circular table 12, disposed vertically, is mounted on the support structure 11 and is rotated by an electric motor 13.

The table 12 carries an annular set of cylindrical forms 14 which can rotate freely about their own axes and each of which can receive a respective pot 15. In particular, each form 14 is screwed onto a spindle 16 which is connected to the table 12 axially but can rotate freely. The interior of each form 14 has an annular cavity 17 which is open at the rear; the front portion of the form has a plurality of through-holes 18 which open into the cavity 17. An electrical resistance 19 having, essentially, the configuration of a cylindrical helix, is fixed to the table 12 near each spindle 16, together with a rod-shaped temperature sensor 20. The electrical resistance 19 is wound around the spindle 16 and is housed in the cavity 17 in order to heat the form 14 and the temperature sensor 20 also extends into the cavity 17 to detect the temperature of the form 14. A control box 21 fixed to the central portion of the table 12 has a series of adjustment knobs 22, each of which enables the temperature of a respective form 14 to be regulated by the switching on or off of the electrical resistance 19 and on the basis of the temperature value supplied by the sensor 20.

Above the table 12 there is a transverse arm 23, one end of which is hinged on a side pillar 25 of the support structure 11 at 24. The opposite end of the arm 23 is connected to a device 26 for adjusting the angular position of the arm. In particular, the adjustment device 26 comprises a handwheel 27 which is connected by means of gears to a nut which is restrained axially and is engaged by a screw 28; the latter is connected to the arm 23 by means of a pin-and-slot connection 29; the gears and the nut are not visible in the drawings. The rotation of the handwheel 27 brings about rotation of the nut and hence axial displacement of the screw 28 which in turn brings about rotary displacement of the arm 23 about the hinge point 24, as shown in Figures 3, 4.

Mounted on the arm 23 is a unit for supplying and collecting a ribbon 30 which is wound into a reel and to which a heat releasable continuous decoration is applied. This supply unit comprises a feed spindle 31 mounted for rotating on one end of the arm 23 and a take-up spindle 32 which is mounted on the other end of the arm 23 and is rotated by an electric motor 33; the rotation of the feed spindle 31 is braked by a friction device not visible in the drawings. The new reel of ribbon 30 is positioned on the feed spindle 31 and the ribbon is unwound therefrom and wound onto the take-up spindle 32 by means of the electric motor 33. A series of rollers 34 defines a path for the ribbon 30 between the

spindles

31, 32 such as to lead a portion of the ribbon along a horizontal plane parallel to a plane tangential to the circular table 12.

A drum 35, also mounted on the arm 23, has a rubberized cylindrical outer covering 36 and is disposed vertically so that the horizontal plane mentioned above in relation to the ribbon 30 is tangential to the rubberized covering 36. The drum 35 is rotated by an electric motor 37. A substantially semi-annular case 38 is also mounted on the arm 23 above the drum 35. Fixed inside the case 38, along its half circumference and near the rubberized covering 36 is a series of infra-red lamps 39 which heat the covering. A temperature sensor 40, also mounted on the case 38 near the rubberized covering 36, enables the rubberized covering to be kept at a predetermined temperature.

The machine is completed by a device 41 for operating and controlling the members of the machine described above, apart from the operation and control of the heating of the forms 14 which, as described above, is effected by means of the control box 21.

The machine 10 described and illustrated operates as follows.

The forms 14 and the rubberized covering 36 of the drum 35 are heated to and kept at a predetermined temperature by the means described above.

The pots 15 to be decorated are then fitted on the forms 14; during this operation, the holes 18 allow the air which is trapped between the pot and the form and which would otherwise hold back the operation, to escape. Once fitted, the pots 15 are heated by the heat of the forms.

When the electric motor 13 is operated, the table 12 is rotated until the cylindrical outer surface of the first pot to be decorated is in tangential contact with the ribbon 30. In this position, the drum 35, which is kept rotating continuously by the electric motor 37, pushes the ribbon 30 onto the cylindrical surface of the pot with its rubberized covering 36. At the moment when this position is reached, the electric motor 33 rotates the take-up spindle 32 in synchronism with the drum 35, that is, in a manner such that the ribbon 30 advances at a speed equal to the peripheral speed of the drum 35. The drum 35 rotates the pot, given that the form on which the pot is fitted is free to rotate.

The heat of the pot and of the covering 36, as well as the pressure of the drum 35 on the pot, transfer the decoration from the ribbon 30 to the cylindrical outer surface of the pot. The synchronous movement of the drum 35, of the pot entrained by the drum, and of the ribbon 30 enable the decoration to be applied correctly along the entire surface of the pot.

Once the pot has rotated through 360° and the decoration has thus been applied along its entire cylindrical outer surface, the electric motor 33 stops and the electric motor 13 is simultaneously switched on and rotates the table 12 until the cylindrical outer surface of the second pot to be decorated is in tangential contact with the ribbon 30. At this point, the decoration cycle is repeated exactly as described above for the first pot. This process can be carried out continuously with the removal of the decorated pots from the forms and the placing thereon of new pots to be decorated.

The pressure with which the drum 35 presses the ribbon 30 onto the pot can be adjusted by means of the handwheel 27 which brings about a downward or upward rotary displacement of the arm 23 about the hinge point 24 and thus brings about an equal displacement of the drum 35 mounted on the arm so as to increase or decrease the pressure.

Naturally other cooking vessels such as saucepans, frying pans, etc. can be decorated in the same manner by variation of the dimensions and/or the shapes of the forms and of the rubberized outer contact surface of the drum. The fact that the drum 35 can be raised or lowered by means of the handwheel 27 permits this adaptation of the machine to vessels of various types since, with vessels of different diameters, the drum 35 will have to be moved correspondingly.

The ribbon 30 with the heat releasable decoration is easily obtainable commercially from specialist companies and the decoration may be of any type and may be produced in one or more colours.

The temperature of the forms and of the covering of the drum is such that the heat transfer of the decoration is made at a temperature of 110°C.

The second machine, shown in the Figures 5,6 and generally indicated 50, is also suitable for decorating pots, like the first machine 10, but is horizontally operating.

For sake of simplicity, in this second machine 50 the elements similar or equivalent to that of the first machine 10 are indicated with the same reference number.

The machine 50 operates as the machine 10 with the difference that the table 12 and the drug 35 are disposed and rotate on a horizontal plane.

The drum 35, the case 38 and the unit for supplying and collecting the ribbon 30 are mounted on a frame 51 horizontally movable along guide rails 52 towards or away from the table 12. A section 53 of the frame 51, on which the drum 35, the case 38 and said unit are fixed, is further angularly movable to incline the axis of the drum 35 together with the ribbon 30 with respect to the axes of the forms 14. Thanks to these movements of the frame 51 the machine 50 can be adapted to different kind of cooking vessels (vessels of different size, vessels having inclined side walls, etc.).

Upstream and downstream wit respect to the machine 50 two

ovens

54 and 55 are respectively provided. A transfer apparatus 56 is also provided for transferring the pots 15 from the oven 54 to the machine 50 and from the machine 50 to the oven 55.

The

ovens

54,55 have each a heating chamber, respectively 57,58, and actuated rollers, respectively 59,60, to move the pots 15 through the oven.

The transfer apparatus 56 comprises two parallel, vertically extensible arms 61 mounted on a common support unit 62 horizontally movable along a guide bar 63. Each arm 61 is provided with a suction end 64 to pick up the pots 15.

In the chamber 57 of the oven 54 each pot to be decorated is heated to a temperature of 90°C. At the output of the oven 54 one arm 61 picks up one pot 15 and transfers it onto one form 14. The machine 50 provides to decorate the pot 15 as seen for the machine 10. Once the pot 15 has been decorated, the other arm 61 picks up the decorated pot 15 and transfers it to the other oven 55. In the chamber 58 of this oven 55 the pot 15 is heated to a temperature of 200°C.

The two arms 61 operate simultaneously: when the first arm 61 transfers one pot 15 to be decorated from the oven 54 to a form 14, the other arm 61 transfers another pot 15 already decorated from the form 14 on which is fitted to the other oven 55.

The third machine, shown in Figure 7 and indicated 70, is intended for heat transfer decoration of a plate from which the cooking vessel is formed, according to the second example of method described above.

The machine 70 comprises substantially a plane 71 along which a series of feeding rollers 72 move the plate, indicated 73, through a heat transfer decoration unit 74. This unit 74 comprises a heated drum 75 and a cylinder 76 parallel and operatively associated to the drum. The carrier of the decoration is constituted by a wide coiled ribbon 77 of polythene paper mounted on a feed spindle 78 disposed on one side with respect to the drum 75 and the cylinder 76; on the opposite side a take-up spindle 79 is provided onto which is wound the paper which is unwound from the feed spindle 78; rollers 80 are further provided which define a path between the

spindles

78,79 such as to lead a portion of the paper along a horizontal plane parallel to the plane 72 between the drum 75 and the cylinder 76. The machine is completed by a unit 81 for operating and controlling the components of the machine described above.

Operatively, the plate 73 is moved by the rollers 72 through the heat transfer decoration unit 74 in the direction of the arrows and specifically passes and is pressed between the heated drum 75 and the cylinder 76 below the paper carrying the decoration. In this way a transfer occurs of the decoration from the paper to the surface of the plate 74.

The plate 73 is rectangular to form a baking-pan.

Naturally, variations and/or additions may be made to what is described and illustrated above.

The carrier may be of any configuration and may be made of silicone paper instead of polythene paper. Both polythene paper and silicone paper guarantee a high quality, definition and permanence of the decoration on the vessel.

As regards the first and second machine, it is pointed out as follows.

The fact that the shapes of the forms and of the drum shown may be varied to adapt the machine to vessels of various types has already been mentioned above.

The form-holder table may have any suitable number of forms.

The electrical resistances and the infra-red lamps could be replaced by heating means of any type. These resistances and lamps have, however been found simple and effective.

As regards the first machine, the arm which supports the ribbon-supply and collection unit and the drum, as well as the members used for adjusting the position of the arm, could also be replaced by equivalent means. However, the arm and the members have been found simple and effective in this case also. Analogous considerations can be made for the second machine.

In the present description, drum means any rotating member which can provide the pressure necessary to apply the decoration to the pot. The outer surface of the drum may be of any material suitable for the use described above. The rubberized covering has, however, been found effective.

Also for the third machine structural and functional modifications can be made to adapt to different shape of the plate (rectangular, square, circular, etc.).

In the present embodiments, the decoration produced on the vessel or the plate is continuous. It is also possible to consider the application of one or more discrete decorations to the vessel or to the plate in any position, either with a continuous carrier on which the discrete decorations are reproduced and, in this case, the machines illustrated are used, or with discrete carrier which are brought to the surfaces to be decorated one by one and, in this different case, the machines will have to be different.

Claims

A method of decorating cooking vessels wherein:

the vessel is coated with silicone resin at least on the surface to be decorated;

a carrier, to which a heat releasable decoration is applied, is provided;

the carrier is brought into contact with the coated surface of the vessel to be decorated, so as to transfer the decoration to the coated surface of the vessel;

heat being supplied to the vessel before, during, and after the decoration is transferred to the vessel.
A method according to claim 1, wherein the vessel is formed from a plate and the silicone resin is applied to the plate before forming the vessel.
A method according to claim 2, wherein the decoration is applied to the plate before forming the vessel.
A method according to claim 1, wherein the transfer temperature is comprised between 100°C and 120°C, preferably 110°C.
A method according to claim 2, wherein:

the plate coated with the silicone resin is heated to a temperature comprised between 130°C and 200°C, preferably 170°C and is cooled,

the cooled plate is moulded to form the vessel,

the vessel is heated to a temperature comprised between 80°C and 100°C, preferably 90°C,

the decoration is transferred to the coated surface of the vessel using a transfer temperature comprised between 100°C and 120°C, preferably 110°C,

the vessel is heated to a temperature comprised between 180°C and 220°C, preferably 200°C.
A method according to claim 3, wherein:

the plate coated with the silicone resin is heated to a temperature comprised between 80°C and 100°C, preferably 90°C,

the decoration is transferred to a coated surface of the plate using a transfer temperature comprised between 100°C and 120°C, preferably 110°C,

the plate with the decoration is heated to a temperature comprised between 180°C and 220°C, preferably 200°C and is cooled,

the cooled plate is moulded to form the vessel.
A method according to Claim 1, wherein the carrier is constituted by a coiled ribbon (30).
A method according to Claim 1, wherein the carrier is made of polythene paper.
A method according to claim 1, wherein the carrier is made of silicone paper.
A machine (10,50) for implementing the heat transfer decoration of the method according to Claim 1, comprising at least one form (14) on which the vessel (15) is mounted, means (31-34) for supplying the carrier in the shape of a coiled ribbon (30) to the surface of the vessel (15) to be decorated, characterized by further comprising a drum (35) which keeps the ribbon (30) in contact with the surface to be decorated, means (19, 39) for heating the vessel (15) and the drum (35), and drive means (37) which bring about the movement of the form (14) and of the drum (35) in association with the means (31-34) for supplying the ribbon (30), first heating means (19;54) being provided for heating the vessel (15) before the decoration is transferred to the vessel (15) and second heating means (55) being provided for heating the vessel (15) after the decoration is transferred to the vessel (15).
A machine according to Claim 10, having a plurality of forms (14) mounted in a ring on a table (12) which is rotated intermittently by drive means (13) to bring the forms (14) with the vessels (15) to the ribbon (30) and the drum (35), one by one.
A machine according to Claim 10, wherein the supply means (31-34) comprise means (32, 33) for collecting the ribbon (30) from which the decoration has been removed.
A machine according to Claim 12, wherein the supply and collection means comprise a feed spindle (31) which is rotated with braking and carries the ribbon (30) with the decoration wound into a reel, a take-up spindle (32) which is rotated by drive means (33) and on which the ribbon (30) which has been unwound from the feed spindle (31) and from which the decoration has been removed is wound, and a series of rollers (34) for guiding the ribbon (30) between the feed spindle (31) and the take-up spindle (32).
A machine according to Claim 13, wherein the drive means (37) which bring about the movement of the form (14) and of the drum (35) are synchronized with the drive means (33) which operate the take-up spindle (32).
A machine according to Claim 10, wherein the form (14) is freely rotatable about its own axis and the drive means (37) which bring about the movement of the form (14) and of the drum (35) act on the drum (35), which rotates the vessel (15) fitted on the form (14).
A machine according to Claim 10, wherein the drum (35) has a rubberized covering (36) on its cylindrical outer surface.
A machine according to Claim 10, wherein the means for heating the form (14) comprise a helical electrical resistance (19) housed in a cavity (17) in the form (14).
A machine according to Claim 10, wherein the means for heating the drum (35) comprise a series of infra-red lamps (39) disposed near the cylindrical outer surface of the drum (35).
A machine according to Claim 10, wherein there are temperature-sensing means (20, 40) which detect the temperature of the form (14) and of the drum (35) for temperature-control and regulation.
A machine according to Claim 10, wherein the means (31-34) for supplying the ribbon (30), and the drum (35), are mounted on support means (23,53) of adjustable position.
A machine according to Claim 11, wherein the table (12) and the drum (35) are disposed vertically.
A machine according to Claim 11, wherein the table (12) and the drum (35) are disposed horizontally.
A machine (50) according to claim 11 in combination with two ovens (54,55), one (54) upstream to and the other (55) downstream to the machine (50), for heating the vessels (15), and in combination with a transfer device (56) for transferring the vessels (15) from the upstream oven (54) to the machine (50) and from the machine (50) to the downstream oven (55).
A machine for implementing the heat transfer decoration of the method according to Claim 3, comprising means (78,79,80) for supplying the carrier in the shape of a coiled ribbon (77) to the surface of the plate (73), a heat transfer unit (74) comprising a heated drum (75) which keep the ribbon in contact with the coated surface of the plate (73) to be decorated, drive means (72) to move the plate along a working plane (71) through the heat transfer unit (74), first heating means being provided for heating the plate (73) before the decoration is transferred to the plate (73) and second heating means being provided for heating the plate (73) after the decoration is transferred to the plate (73).